Photographic storage system



Oct. 8, 1963 s. P. NEWBERRY PHOTOGRAPHIC STORAGE SYSTEM 5 Sheets-Sheetyl Filed June 27, 1957 INM.

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OCL 8, 1963 s. nfNEwBERRY PHoToGRAPHIc STORAGE SYSTEM 5 Sheets-Sheet 2Filed June 27, 1957 Oct. 8, 1963 sQP. NEWBERRY PHOTOGRAPHIC STORAGESYSTEM 5 Sheets-Sheet 3 Filed June 27, 1957 Oct. 8, 1963 s. P.NEwBr-:RRY

PHoToGRAPmc STORAGE SYSTEM 5 Sheets-Sheet 4 Filed June 27, 1957 f W q fwn 0, ig vd n his W Q lfm d v n e IIIIIII J f g n u lv 21mm IL NRW I. I@I Q11 N MII Wb llllnlllll I III Il' Il! Ivi. .M h .Il dd. w ml f m 5 #VUnited States Patent O 3,106,700 PHOTOGRAPHIC STORAGE SYSTEM Sterling I.Newberry, Schenectady, N.Y., assignor to General Electric Company, acorporation of New York Filed June 2.7, 1957, Ser. No. 668,490 7 Claims.(Cl. 340-173) This invention relates to a method and apparatus for datastorage and, more particularly, a photographic memory system of largecapacity, high storage density, high reliability, and rapid access.

There is an urgent and growing need for a memory having very largecapacity with rapid access to any part of the memory at high reliabilityof readout. This is especially important lfor maintaining necessaryflexibility in automated production lines, industrial record files,computer applications, as well as the numerous other areas where datastorage is desired. The use of a photographic emulsion as the recordingmedium presents an extremely promising approach since modern emulsionsof very high quality and high resolving power are available. In thepast, however, the storage densities in systems utilizing photographicemulsions were so low as to make them essentially useless for highcapacity and fast access stonage systems.

The limits on storage density in the past have not been from theresolving power of the photographic emulsion but from artifacts causedby dust :and scratches and `from difficulties with tracking errors anddata relocation. Because of the low storage density, storage elements ofsubstantial size are necessary in order to store an adequate amount ofdata and, as a consequence, special handling to eliminate eifects ofdust particles, such as hermetic sealing or total oil immersion, isimpractical. Furthermore, because of the size of the elementssubstantial relative movement between the storing and reading heads andthe storage element are necessary to store and have access to all of thedata. This results in scratches and other marring effects on the filmsurface further reducing the resolution. In addition, low storagedensity and large storage elements demand exact mechanical location ofblocks of data during readout which requires a formidable level ofmechanical precision and, consequently, complex and expensive equipment.

By utilizing an electro-optical system including a reduced and focussedbeam of light generated by a stream of electrons striking thefluorescent surface of a cathode ray device, it is possible to produce astorage density of approximately 106 storage sites per square centimeterwhich is greater by a factor of l()3 than the photographic storagesys-tems hitherto known. With such high storage densities the problem ofdust land scratches is eliminated by hermetically sealing the small areaof photographic film required for large capacity storage. The problem ofregistering during readout also is immensely simplified by virtue of thefact that it becomes possible to utilize a rough mechanical register tobring the desired area of stored data into position and thenelectrically shifting the scanning center of an image tube which readsthe data from the magnified image of the data until exact centering andregistration of the desired block of data is achieved.

It is an object of this invention, therefore, to provide a photographicdata storage system of extremely large capacity :and high storagedensity.

A further object of this invention is to provide a photographic datastorage system which is not limited in reso'- lution by dust particlesand scratches.

It is another object of this invention to provide a photographic datastorage system having a storage element of sufficiently small dimensionto permit sealed handling thereof.

Yet another object of this invention is to provide a photographic datastorage system which permits rapid access to any portion thereof bysimple mechanical register and readout of information in the selectedportion by an electro-optical system.

Yet another object of this invention is to provide a photographic datastorage system wherein a simple mechanioal movement provides a roughregister and shifting of the scanning pattern of an image deviceprovides the precise registration.

Other objects and purposes of the invention will become apparent as thedescription thereof proceeds.

In accordance with the invention the foregoing objects are achieved byutilizing -a spot of light from a kinescope flying spot device, reducingIthe size of the light spot by means of an optical device and focussingit on a photographic element in a predetermined sequence to produce datamatrices in binary `form as black and white dots. By virtue of thistechnique, storage density of the order of 106 storage sites per squarecentimeter are achieved.

During readout the high capacity and high storage density photographicdata element is utilized under hermetically sealed conditionseliminating problems of dust and scratches :and the data stored thereonis projected `onto the face of the image tube device and readoutthereby. The image tube sean is shifted electrically in response to-data stored on the photographic element to relocate the information inthe image plane so that only approximate mechanical registration isnecessary.

The novel features which are believed to be characteristic of thisinvention are set forth with particularity in the appended claims. Theinvention itself, however, both as to its organization and method ofoperation together with further objects and advantages thereof may bestbe understood by reference to the following description taken inconnection with the accompanying drawing in which:

yFIGURE 1 represents an embodiment of an apparatus for storinginformation on a photographic element;

FIGURE 2 represents la detailed showing of the scanning martrix andcurrent adders of FIGURE l;

FIGURE 3 represents an embodiment of a readout apparatus for the storagesystem;

FIGURE 4 is a detailed showing of the scanning matrix :and the means forshifting .the image tube can; and

FIGURE 5 is a diagrammatic illustration of the relative position of thestored information and the image tube scan before relocation.

ln the embodiment of the invention, as illustrated in FIGURE 1, aphotographic storage element 1 consisting of a high resolution emulsion2 mounted yon a transparent glass backing plate to provide dimensionalstability is rigidly fixed to a metal frame element illustrated at 3 andis henmetically sealed in a casing 4 to eliminate dust particles andscratches on the photographic ernulsion. A rack and pinion element 5,shown diagrammatically, is provided for positioning the storage element1 both in the horizon-tal and vertical directions, and may be manuallyoperated or driven by a servo-mechanism device. A kinescope 6 on theiiuorescent screen of which is produced a raster utilized as a spotlight source is positioned at the conjugate focal position of aprojection light microscope 7 which reduces and focuses the light spotfrom the kinescope onto the photographic emulsion to produce discrete 10micron diameter light and dark spots, in the form of a matrix, whichrepresent the da-ta to be stored. The individual bits of datarepresented respectively by the light and dark spots are placed onapproximately 10 micron centers in the form of a 32 x 32 binary matrix,covering an area of approximately one-tenth of a square millimeter.

The kinescope 6 has a fluorescent viewing screen 8 and a source ofelectrons 9 consisting of an electron emitting cathode and anaccelerating grid. A focusing coil 11 and an alignment coil 12 arepositioned to control the trajectory of the electron beam in thekinescope tuoe in a well gnown manner to focus and align it with res ectto the optical axis of the tube. Vertical and horizontal deflectingcoils 13 and 14 constitute the means by which the electron beam is swept`across the face of the fluorescent viewing screen S both in thehorizontal and vertical directions to produce the flying spot source oflight. A power supply, indicated `generally at 15, provides energizationfor the cathode of the kinescope element 6 as well as for the focussingand alignment coils 11 and 12.

The horizontal and vertical deflection coils 13 and 14 are connected toa beam deflection coil supply circuit 2f) which produces a staircasedeflection current for deflecting the electron beam as a step scan toproduce the flying spot of light. The precise construction and manner ofoperation of the beam deflection supply circuit will be explained ingreater detail later with reference to FIGURE 2.

The projection light microscope 7 which reduces the flying light spot onthe face of the kinescope 6 and focuses it onto the photographic storageelement comprises a color-corrected achromatic amplifying lens systern16 positioned adjacent to the fluorescent screen 8 of the kinescope,which lens assembly comprises a projection lens element, fieldflattening lens element, and a field lens. Positioned at the oppositeend of the microscope and adjacent to the field photographic element 1is a color-corrected achromatic objective lens system 18 which, inconjunction with the amplifying `lens 16, reduces the light spotproduced by the kinescope and focuses it onto a photographic element 1.A focus control assembly 17 positioned intermediate the lenses 16 and 18permits manual or, if desired, automatic adjustment of the focus of the`microscope 7.

In order to provide step scanning of the electron beam to produce theflying spot of light, it is necessary that the beam deflection coilcurrents for the kinescope 6 be in the form of a staircase. This isaccomplished by means of the deflection circuit 20 comprising a scanningmatrix 21 comprising horizontal and vertical scaling circuits 22 and 23,as seen most clearly in FIGURE 2, and the horizontal and verticalcurrent adder circuits 24 and 25. FIGURE 2 illustrates partially inblock diagram form both the horizontal and vertical scalers and currentadded circuits wherein the vertical scaling circuit 23 is fed from theoutput of the horizontal Scaler 22.

The horizontal scaling circuit 22 has a pulse input terminal 27 andcomprises :a number of bi-stable multivibrator circuits 26 arranged as abinary scaler circuit. Each of the bi-stable multivibrators, one ofwhich is shown in detail, controls one stage of the current adder 24consisting of a constant current generator circuit '29, such as constantcurrent pentode, for example.

Each of the bi-stable circuits 26 consists of multivibrator connectedtube pairs V3 and V4 and a pair of trigger tubes V1 and V2 having asingle common input and which are normally non-conducting by virtue ofthe negative biasing voltage applied to their grids. Whenever a positivepulse arrives on the input, V4 and V2 conduct transmitting a negativepulse to the tubes V3 and V4. Whichever of the tubes is non-conductingis, of course, not affected while the conducting tube is cut off by thenegative pulse which, by virtue of the multivibratory connection,reverses the conducting states of the two tubes. The `hi-stable circuitremains in this new state until the arrival of the next pulse whichcauses it to reverse its state. The output from each lai-stablecircuitry 26 drives the next succeeding one by coupling the output pulsefrom tube V4 to the input lead of the trigger tubes V1 and V2 of thesucceeding bi-stable circuit 26.

At the initiation of horizontal Scaler operation each of the V3 tubesare conducting and tubes V4 are non-v conducting and the application ofpulses to the terminal 27 of the scaler starts operation thereof. It isclear that each time a tube V4 in a bi-stable circuit changes from aconducting to a non-conducting condition, a positive pulse is introducedto the input of the next bi-stable circuit in the series causing it tochange its state. As is well known, scalers of this sort are known `as2n types and require n bi-stable circuits to scale 2n pulses. For a moredetailed description of such scaling circuits reference is made to HighSpeed Computing Devices, Engineering Research Associates, McGraw-HillBook Company, lnc., New York (1950), and particularly chapter 3 whichcontains an excellent discussion of the principles and operation of suchscaling circuits.

The output from the last horizontal bi-stable multivibrator is connectedto the first vertical bi-stable multivibrator 28 through a lead 3f) toshift the scan by one line at the end of each horizontal scan. That is,at the end of a horizontal line scan when all of the horizontal bistablemultivibrators 26 are on, the next clock pulse resets the horizontalScaler to zero and the output pulse is fed to the first bi-stablemultivibrator element 28 of the vertical Scaler 23 and shifts the scanby one line.

Each of the bi-stable devices 26, as has been stated previously,controls one of the constant current generators 29 of the respectivecurrent adders 24 and 25 by virtue of triggering pulses aplied theretoby a lead 31 from the anodes of the tubes V3. Thus each time a tube V3in a bi-stable circuit changes from a conducting to a noncomz'zlctngstate, a positive pulse is applied to the respective current generators29 to initiate operation, while a change from l10n-conduction toconduction produces a negative pulse which terminates operation of thecurrent generator.

The vertical scanning and current adder circuits 24 and 25 operate inthe same manner as do the horizontal counterparts described above toproduce a vertical step scan with the output from the last horizontalbi-stable multivibrator element, indicating the completion of onehorizontal scan, triggering the first vertical bi-stable element 28 toshift the scan. Each of the binary Scaler circuits 22 and 23 as isstandard practice in such devices feed back from the last stage thereofto the first stage in order to reset the sealer at the end of the scan.Thus, the horizontal Scaler 22 is reset at the end of every 32 pulsesWhereas the vertical Scaler 23 is reset at the end of 1,024 pulses thusproducing a scan over a 32X 32 matrix.

The staircase deflection current may be produced not by addingsuccessive equal increments of current, requiring a separate currentgenerator for each increment, but generally by selectively addingcurrent increments of the 2n from (i.e., 201, 211, 221, 21I, 2111) whichmakes it possible to produce a staircase of 2 steps with n-l-l currentgenerators. Thus, to produce a 32 step staircase deflection current (25steps) only 6 current generators and their associated bi-stable elementsare necessary rather than 32. To illustrate the principle assume that,for simplicity of explanation, a 7 step staircase is desired; if equalincrements are to be added then 7 current generators are necessary whichare successively turned on to produce the 7 incremental current steps.On the other hand, if current generators producing output currents whosemagnitudes are related by a 2n, where factor then only 3 are necessary.That is, 3 current generators having currents of the followingmagnitudes,

r." .s 201, 211, and 221, may be selectively actuated to produce thestaircase as shown in the following table:

As can be seen from the above table, the on-off sequences of therespective current generators follow the counting sequence of a binaryscaler such as the horizontal Scaler 24.

The binary scaler illustrated in FIGURE 2 and the constant currentgenerators associated with the individual elements thereof, are soarranged that n-{-lbistaible multivibrator elements are utilized for astorage matrix of 2n and the output currents from each of the constantcurrent generators is adjusted to have a two-to-one ratio of currentbetween any two successive stages so that the selective actuation of thebi-stable element and their associated constant current generatorsprovide the desired staircase deection coil current. However, it isobvious, as pointed out previously, that scaling circuits other than ofthe type illustrated and described may be utilized to produce thedesired deflection coil current wave.

In order to store data on a photographic storage element, such as isillustrated in FIGURE l, in binary form as black and white dots, it isnecessary to blank the spot of light produced by the flying spotscanning kinescope element 6, periodically so that discrete areas areselectively exposed to produce the black and white dots. To this end ablanking circuit 32 which provides voltage to blank the electron beam ofthe kinescope in synchronism with the data to be stored is connected tothe accelerating and blanking grid 9 of the kinescope 6. A pair ofterminals 33 and 34 provide, respectively, a source of synchronizingclock pulses and the stored data in binary form i.e., pulse or no pulse)which are used to blank the electron beam of the kinescape 6. Theterminals 33 and 34 may be connected directly to the output terminals ofa computer with the terminal 33 connected to the clock pulse generatorof the computer and the terminal 34 being connected to the data outputterminal of said computer.

The synchronizing clock pulses appearing at the terminal 33 areconnected by means of a suitable conductor to the scanning matrix 21 ofthe sweep circuit 20 and to the input terminal 27 thereof to provide thetriggering pulses for the scalers to produce the proper deflection ofthe electron beam. The clock pulses from the terminal 33 are also fed,over another conductor, to the input of a gate 35, indicated in blockdiagram form but which may, for example, be a tetrode, which also hasapplied thereto the stored data blanking information from the terminal34. The data representing blanking pulses from the terminal 34 functionas the gating signal for the gate 35 and permits passage of clock pulsestherethrough only on the occurrence of a pulse from the terminal 34.That is, as has been pointed out, the pulses from the terminal 34 are inbinary form; i.e., pulse or no pulse, and thus a clock pulse ispermitted to pass through the gate 35 upon the occurrence of a pulse atterminal 34 and none is permitted to pass through during the no pulsecondition at this terminal. Thus, clock pulses passing through the gate35 may then be utilized as blanking pulses for the kinescope.

Connected to the output of the gate element 35 is an amplyfying andpulse shaping and clipping circuit, indicated generally in block diagramform at 36, which functions to amplyfy the clock pulses passed throughthe gate and to reshape them into steep-fronted square wave pulses inthe event the wave shape has degenerated during passage through thecomputer and the gate 35. The reshaped and amplified clock pulses arethen fed by means of a suitable conductor to a delay line 37 in order todelay their application to the accelerating and blanking grid 9 by asuflicient amount to insure that the electron beam has moved to its newscan position prior to the pplication of the blanking signal. There is,since the clock pulses from the terminal 33 are utilized both to triggerthe scanning matrix of the kinescope sweep circuit 20 as well asproviding the blanking voltage for said kinescope, it is necessary thatthe application of the blanking pulse to the grid 9 be delayed until theelectron beam has been swept to its new position. Under certaincircumstances it is possible that the delay inherent in the gate and theamplifying and clipping circuits may be suiciently large to eliminatethe need for a delay line; however, it should be kept in mind that thetime delay in the scanning circuits 2t) and the blanking `circuits 32must be equal in order to insure that the blanking of the beam takesplace only after the beam has moved to its new scan position. Thus, itcan be seen that the blanking circuit illustrated at 32 provides themeans by which the light spot produced by the kinescope element 6 iscontrolled to produce discrete white and blank dots upon thephotographic storage element l which dots represent the data to bestored in binary form.

In the data storage system illustrated in FIGURE 1, the pulsed fyingspot light source is reduced and projected directly onto a highresolution photographic emulsion which constitutes the ultimate storageelement. However, in some cases it may be desirable to utilize a twostage process wherein the data is -irst stored on an intermediatestorage element of medium resolution by means of a pulsed fying lightspot scanner and optical microscope combination and is then furtherreduced and stored on a high resolution photographic element whichconstitutes the ultimate storage element by means of a source of lightand another optical microscope of the type illustrated and describedwith reference to FIG- UREl.

The general system of the present invention which has been describedwith reference to FIGURES 1 and 2 for storing data on a photographicstorage element by imaging a flying light spot on a photographictransparency constitutes a preferred embodiment of a system for storingsuch data on a photographic plate which information is to be read-out bymeans of an electro-optical readout system presently to be described andillustrated in FIG- URE 3. However, it is possible to store data inbinary form on a photographic storage element with the desired highstorage density by means of a focussed, charged particle beam of thetype produced by the electron-optics of an electron microscope or anX-ray microscope. Such an apparatus and method is described in thecopending application of Sterling P. Newberry, Serial Number 668,489,tiled Iune 27, 1957, now abandoned, and assigned to the General ElectricCompany.

Assuming that the data has been stored on a photographic storage elementby an apparatus of the type described it, consequently becomes necessaryto provide means by which such data may be read out. FIGURE 3illustrates such a readout system which is characterized generally bythe fact that an optical projection system enlarges and projects thestored data onto the surface of an image storage tube which translatesit into a series of representative electrical pulses. The projectedimage of the information matrix and the scanning field of the storagetube are aligned by electronically shifting the eld of scan of thestorage tube until perfect alignment is achieved at which time theoutput and readout circuits of the apparatus are activated to produceoutput signals representative of the data.

Adverting now directly to FIGURE 3, there is illustrated a photographicstorage element 40 of the type discussed with reference to FIGURE lconsisting of a hermetically sealed high resolution emulsion mounted ona transparent backing plate which contains stored data in the form of32x32 matrices of discrete light and dark spots. A rack and pinionelement, illustrated at 41, is fastened to the storage element andprovides a means for positioning the storage element to bring selectedmatrices into the field of view of a readout means presently to bedescribed, which positioning means may be either manually operated ordriven by a servo mechanism device. For the sake of simplicity only therack and pinion for positioning the element in a single direction, thevertical, is shown; however, it is understood that a complementaryhorizontal positioning means is also utilized.

Positioned on one side of the photographic storage element is a sourceof radiant energy such as an incandescent lamp 42 which, in conjunctionwith a heat absorbing means 43, a filter 44 and a condenser lensassembly 45 projects a beam of light onto the photographic storageelement in order to produce a light image of the matrices which, inturn, is amplified by means of a projection light microscope 46positioned on the other side of the storage element.

The projection light microscope 46 projects the enlarged image onto theface of an image storage tube 47 which, in turn, translates the matrixinto a series of electrical output pulses representative of the data.The projection light microscope is of the same type illustrated anddiscussed with reference to FIG. l and comprises a color-correctedachromatic objection lens system 49 positioned adjacent to the storageelement 40 and a colorcorrected achromatic amplyfying lens system 48positioned adjacent to the face of the image storage tube 47. A focuscontrol assembly 50 is positioned intermediate the lenses 48 and 49 andpermits manual or automatic adjustment of the focus of the microscope46.

The storage tube 47 which has the information matrix applied thereto asa light pattern is of photoconductive target type which has itsphotoconductivity varied to produce an output pulse train representativeof the light pattern. Such a photoconductive image storage tube,commonly known in the art as a vidicon, consists of an electron beamsource 5l including an electron emitting filament, an accelerating anode52, a fine mesh screen 53, positioned adjacent to a photoconductivetarget assembly. The photoconductive target assembly is positioned tointercept the electron beam and consists of a glass plate 54, atransparent conducting back plate and a photoconductive plate 56.Focussing and alignment coils 57 and 5S are positioned to control thetrajectory of the electron beam in a well known manner to focus andalign it with respect to the optical axis. A power supply, indicatedgenerally at 59, provides energization for the electron source 51 aswell as the coils 57 and S8. First and second vertical deflecting coilpairs 6i) and 61 and corresponding horizontal deflecting coil pairs 62and 63 constitute the means by which the electron beam is swept acrossthe face of the photoconductive target 56 in a desired sequence toproduce the output pulse train representative of the binary information.

Photoconductive storage tubes such as the vidicon are based on theprinciple that the focussing of a pattern of light on thephotoconductive target causes its conductivity to increase at the areaswhich are illuminated. Since the target conductivity varies with theintensity of the light, the discrete elements or areas shift theirpotential positive by varying amounts because of leakage currents to thetransparent conducting plate 55 and in this manner a pattern ofpotential variation is established on the target surface 56corresponding to the input light signal. The electron beam produced bythe beam source 51 is scanned across the target and produces capacitycurrent variations which flow to the conductive back plate S5 producingvoltage variations corresponding to the input light signal across anoutput resistor R0 connected to the plate 5S. The output polarity ofthis device is negative in the sense that an increasing amount ofincident light on a target element causes a greater negative variationin voltage across the output resistor R0 when the corresponding elementis scanned by the beam. Thus, by projecting the image of a matrixconstituted of discrete, exposed and unexposed spots onto thephotoconductive target a series of output pulses in binary form (i.e.,pulse or no pulse) are produced with the pulse representing an exposeddiscrete area, and no pulse representing an unexposed area. In thisfashion it is quite clear that the output puise train faithfullyrepresents the data stored on the photographic storage element 40.

rfhe respective vertical deflection coil pairs 6ft and 61 as well as thehorizontal pairs 62 and 63 are connected to a beam deflection coilcurrent supply circuit, indicated generally at 70, which produces astaircase shaped deflection current for scanning the electron beam ofthe vidicon 47 in a step-wise fashion across the photoconductive target56. The deflection circuit 70, broadly speaking, includes a maindeflection circuit channel having a first scanning matrix 7l controllinghorizontal and vertical current adders 72 and 73 to produce a staircaseshaped deflection coil current for scanning the 32x32 matrix projectedonto the vidicon tube.

ln addition, there is provided an auxiliary deflection circuit channelfor electronically shifting the vidicon scan until there is alignmentbetween the tube scan field and matrix projected thereon and whichincludes a second scanning matrix 74 controlling a second pair ofhorizontal and vertical current adder circuits 75 and 76. The actualconstruction and manner of operation of the beam deflection supplycircuit '70 will be explained in detail with reference to FIGURE. 4, atthis point, however, suffice it to say that the beam deflection circuit70 operates in such as fashion that the auxiliary deflection circuitchannel 74, 75 and 76) function to shift the scan plaire of the vidiconuntil a particular information bearing 32X 32 matrix is coincident withthe scan field of the vidicon, at which time it is inactivated and themain deflection channel is actuated to scan the matrix.

The pulse train output from the vidicon 47 appearing across the resistorR0 is fed by means of any convenient lead to the input of an amplifyingmeans 66 and in turn to a pulse shaping circuit 67 which sharpens thewave shapes of the amplified vidicon output pulses. The vidicon outputpulses appearing on the lead 65 are also applied to the coil deflectioncircuit 7i) in order to disable the auxiliary scan shifting circuit andactuate the main deflection circuit when the scan field is aligned withthe 32x32 matrix in a manner which will be xplained in detail withreference to FIGURE 4.

In order to provide an additional check on the alignment and focus thedata matrix and in order to provide a read command signal to the readoutcircuitry to be described presently, there is provided a monitor circuit77 comprising an electrostatic deflection cathode ray tube 73, thedeflection voltage of which is obtained from the beam deflection circuitthrough a monitor sweep amplifier 79. The vidicon pulse output isapplied to the CRT by means of a lead 89 coupled to the control grid ofthe CRT (not illustrated) from the output of pulse shaper 67. Since aseries of pulses corresponding to the black and white dot patterncomprising the stored information are generated as the electron beamscans the vidicon target, the application of this pulse train to the CRT78 whose deflection voltage is in synchronism with the vidicon coildeflection voltage makes it possible to observe visually when thevidicon scan field is coincident with the information bearing 32 32matrix at which time the readout circuitry may be actuated in order toproduce output pulses representative of the stored data. In this fashionan additional safeguard is provided to insure that the output of thesystem contains no ambiguities due to a misalignment of the data matrixand the vidicon scanning system.

`In order to insure that the output pulses from the data storage systemare uniform in shape and as precisely timed as possible, the outputsignal -is composed, not of the amplified and shaped vidicon outputpulses themselves, but of clock pulses gated by the vidicon output pulsetrain. This is accomplished by `applying the vidicon output pulses fromthe pulse shaping `circuit 67 to a readout .gate means wherein thegating of a source of clock pulses by the vidicon output signal takesplace. To this end a clock pulse generator means 81, illustrated inblock diagram form, which may be either a blocking oscillator,yfree-running multivibrator or .the like, produces outpu-t pulses havingsome constant predetermined repetition nate. The clock pulses from thegenerator 81, in addition to being utilized as the output pulses fromthe data storage system, provide the triggering pulses for operating the-scanning matrices 71 yand 74 of the main deflection circuit 70 beingapplied thereto by means of any convenient lead 82.

rPhe lgating of the clock pulses from the generator 81 to produce theoutput pulses is achieved by a pair of gates 68 and 69 denominated asreadout synchronizing gate, and a readout gate respectively. The readoutsynchronizing gate 68, which may be a pentode or any other sirnilar wellknown gating arrangement, makes certain that readout is initiated onlyat the beginning of the vidicon scan. Accordingly, the readoutsynchronizing gate 68 is opened and closed by means of a readoutsynchronizing signal generated by a readout control circuit 83 which isactuated by output pulses from the scanning matrix produced at the endof the previous scan `and prior t the beginning of each vidicon scan.The readout control circuit 83, indicated in block diagram form for thesake of simplicity, may be a bistable multivibrator, `for example, whichproduces a synchronizing gate signal in response to a triggering pulsefrom the decction circuit 7) applied by means of any convenient lead 84.As will be explained in detail later, with reference to FIGURE 4, thereset pulse from the vertical scaling circuit lof the deflection circuit7 ti produced at the end of each 32x32, scan is applied to the controlcircuit `83 to produce the synchronizing signal for the gate 68.

In addition, a readout command circuit 85 is connected to the circuit 83to insure that a readout synchronizing signal is produced only whenreadout is actually desired. The circuit 85 maybe a manually operatedswitch which enables the control circuit 83 and makes it :responsive tothe appearance of the trigger pulse on the lea/d 84.

In operation the control circuit `8S is manually operated after thealignment and focus of the data matrix on the vidicon target has beenchecked by means of the monitor CRT 7S. At this time a read commandsignal from the control circuit 85 actuates the readout control circuit83 permitting a pulse from the scanning matrix to open the readoutsynchronizing gate at the completion of the next scan. The synchronizingsi-gnal from the readout control circuit 83 is applied to the gate 68opening it. The gate `68 stays open d-uring the remainder of the scanallo-wing the shaped vidicon output signals from the pulse shapingcircuit 67 to pass to the readout gate 69. At the termination of thescan another pulse from the deilection circuti 70 is transmitted by thelead 84 tothe readout control circuit S3 terminating the synchronizinggate pulse and closing the readout synchronizing gate 68 until theinitiation lof another scan. The vidicon output pulses which have beenpassed through the gate 68 are applied to the readout of gate 69 and actas gating signals to permit the passage yof clock pulses from the clockpulse generator 81, which clock pulses are applied to any desirableutilization circuit and represent the data stored on the photographicdata storage element 4t).

Before proceeding with the description of the beam deflection coi-lsupply circuit 7 0, which is shown in detail in FIGURE 4, it will beuseful to discuss brieily the under-lying reasons and objectives whichconstitute the basis for the particular approach chosen. As has beenpointed out previously in the introductory remarks, one of the objectsof the instant invention is to produce a data storage system utilizing aphotographic storage elemen-t of high storage density in which selectedblocks of data in 32x32 matrix form are located by means of a roughmechanical registering means and then producing exact centering andregistration of the desired block of data by electricaly shifting thescanning center of the image tube. Hence, it is no longer necessary toprovide high precision mechanical registering means in order to locatethe blocks of data.

FIGURE 5 illustrates, schematically, the relative position of the 32x32matrix and the vidicon scan eld immediately after vthis block of datahas been roughly registered by means of the rac-k and pinion. Theprojected image consists of a 32X 32 matrix of discrete light and darkspots "a representing the data and denominated by the legend matrixOifset and partially over-lapping the matrix is the vidicon scan field,identified by the legend vidicon scan, which is initially located to theleft and slightly above the matrix. Located at the upper left handcorner of the matrix is a relatively large indexing mark B which, aswill be pointed out in detail later, provides a registering pulseindicating that exact centering and registration of the desired block ofdata has been achieved and which inactivates the auxiliary deilectionchannel and actuates the main deflection channel in order to providescan of the photoconductive target.

Exact centering `of the vidicon scan may be achieved, generallyspeaking, by initiating the vidicon scan in the odset positionillustrated in FIGURE 5 until the indexing mark B is reached, at whichtime a registering pulse is produced which disables the auxiliarydeflection channel. The auxiliary channel thus produces a biasingdeilection current the magnitude of which is related to the deflectionnecessary to locate the matrix precisely at which time the maindellection circuit takes over and produces the main deflection currentwhich is superimposed on the biasing deflection current and which causesthe actual readout scanning of the information bearing matrix.

In order to provide the above described action there is providedelectronic circuitry, illustrated in detail in FIGURES 4a and 4b, whichcan be broken down broadly into four major components: (l) MainDeflection Coil Current Channel, (2) Auxiliary Deection Coil CurrentChannel for electronically shifting the vidicon scanning until thematrix is located, (3) Switching Means to apply the clock pulsesselectively to the main and auxiliary channels, and (4) Resetting Meansfor the Switching Means.

Main Deflection Coil Current Channel Referring now to FIGURES 4a land4b, the main deection channel comprises, broadly speaking, a scanningmatrix 71 consisting of horizontal and vertical scaling -circuits '71a(FIGURE 4a) `and 71b (FIGURE 4b) with the vertical circuit driven fromthe output of the horizontal scaler. Horizontal and vertical addercircuits 72 (FIGURE 4a) and 73 (FIGURE 4b) are connected respectively tothe horizontal and vertical scaling circuits.

The horizontal scaling circuit 71a and the vertical scaling circuit7111, in a manner similar to that described with reference to FIGURE 2,comprise a number of bistable multivibrator circuits arranged as binary`Scaler circuits. Each of the bi-stable multivibrators, one of which isshown in detail in each scaler, controls one stage of their respectivecurrent adders consisting `of a constant current generator 86 which may,for example, consist of a constant current pentode.

Each of the bi-stable circuits 85 consist of a pair of multivibratorconnected tubes V3 and V4 and a pair of normally noneconducting triggertubes V1 and V2 having a single common input. The arrival of a positivepulse on the common input lead of the trigger tubes V1 and V2 causesthem to conduct and pass a negative pulse to the multivibrator connectedtubes V3 and V4 thus, causing them to reverse their state and remainthus until the appearance of the next input pulse. The output from eachof the bi-stable circuits drives the next succeeding one by coupling theoutput pulse from the tube V4 to the input lead of the trigger tubes V1and V2 of the succeeding bi-stable circuit SS. In this fashion apositive pulse is introduced into the input of the next bi-stablecircuit in the series each time the tube V4 from a conducting to anon-conducting condition, thus producing a sealer of the sort known asthe 2 type.

The constant current generator 86 of the current adder circuit are eachconnected to the tubes V3 of each of the multivibrator connectedcircuits. Thus, each time a tube V3 in the circuit changes from aconducting to a non-conducting state, a positive pulse is appliedy toits particular constant current generator S6 to initiate operation whilea change from non-conduction to conduction produces a negative pulsewhich terminates operation of the current generator. As described withreference to FlGURE 7., there will be produced at the output lead of thecurrent adders a dellcction coil current in the form of a staircasewhich causes the electron `beam of the vidicon tube to scan thephotoconductive target in a stepwise fashion.

Each of the binary sealer circuits 71a and 71b, as is standard practicein such devices, feed back from the last stage thereof to the tirststage in order to reset the sealer at the end of the scan.

Auxiliary Deflection Coil Current Clzannel The auxiliary delieetionchannel 74 in a similar fashion comprises a horizontal scaling circuit74a (FIGURE 4a) and a 'vertical scaling circuit Mb (FIGURE 4b) actuatedfrom the output from the horizontal scaling circuit. A horizontalcurrent adder 7S and a vertical current `adder 75 are connected to therespective horizontal and vertical scaling systems in the mannerdescribed above to produce the respective deflection coil currents in astaircase form. The horizontal sealer 74a and the vertical sealer 74hconsist of a number of bi-stable multivibrator circuits 37 arranged as abinary sealer circuit with each of the bi-stable elements controllingone stage of its respective current adder, each consisting of a constantcurrent generator S. Since the auxiliary deflection circuit and thecomponents constituting it operate in precisely the same manner as themain deection channel described above, the operational description neednot be repeated here. Each of the horizontal and vertical current addersand both of the main and auxiliary deflection channels are connected totheir respective vertical and horizontal deflecting coils shown anddescribed with reference to the vidicon of FIGURE 3.

Selective Switching Means In order to apply the clock pulses from theclock pulse generator 8l ot FGURE 3 selectively to the auxiliary andmain delleetion channels, a switching means 89 shown in FIGURE 4o at theupper left-hand corner is provided which applies the clock pulsesselectively to the auxiliary channel 74- for electronically shifting thevidicon scan until exact registration of the matrix is achieved and thento the main deflection channel to initiate the stepscan of the matrix.To this end an input terminal 90 connected to the clock pulse generator81 has the clock pulses which actuate the scaling circuits appliedthereto. The clock pulses appearing at the terminal 90 are appliedthrough a coupling capacitor 91 and a lead 93 to a normally open gate 92and a normally closed gate 94 which control the application of the clockpulses to the auxiliary and main channels respectively.

The normally open gate means 92 comprises a tetrode vacuum tube, theanode of which is connected to a source of operating potential through asuitable anode resistor and the cathode to a source of referencepotential, such Cir 12 as ground, through a cathode resistor. The lead93 from the input terminal 9i) is connected to the control electrode ofthe tetrode 92 while the cathode is connected` by means of a suitablelead to the input of the horizontal scaling circuit 74a.

The normally closed gate means 94 similarly comprises a tetrode vacuumtube, the anode of which is connected to a `source of operatingpotential by means of an anode resistor and the cathode directly to asource of reference potential, such as ground. The control electrode Maof the normally closed gate means 94 is connected directly to the anodeof the normally open gate 92. Thus, while the normally open gate 92 isin its conducting condition and passing clock pulses to the auxiliarychannel, the normally closed gate 94 is maintained non-conducting byvirtue of the anode drop of the tube 92 and does not permit theapplication of clock pulses therethough, thus maintaining its associateddel'lection channel 7l in a quiescent state. As soon as the normallyopen gate 92 is made non-conducting its anode potential rises, andunblocks the normally blocked gate 94 thus applying clock pulses to themain detiection channel, the input terminal of which is connected to theanode of the gate 94. In this fashion the clock pulses which actuate therespective dellection channels are selectively applied either to theauxiliary or main channels.

There is provided, in addition, a triggering means, actuated in responseto a positive pulse produced whenever the electron beam of the vidiconscan strikes the registering mark B on the 32x32 matrix, to close thegate 92 and open the normally closed gate 94 to initiate scanning of thenow exactly registered matrix. There is provided a gaseous trigger tube9S, which may be a thyratron or the like, having a cathode, controlelectrode, and an anode. The anode of the gaseous tube is connected to asource of operating voltage by means of a suitable anode resistorwhereas the cathode is connected to a source of reference potential suchas ground while the control electrode is connected to a movable tap on apotentiometer connected in shunt with a source of negative biasingvoltage 96 such as a battery. As is well Aknown to those skilled in theart, such gas tubes may be maintained in a non-conducting condition bymeans of such a critical negative bias until the bias is overcome atwhich time the tube conducts and remains in a conducting condition untilthe anode potential is reduced suiciently to extinguish conduction.

The anode of the gaseous trigger tube 95 is directly coupled to thescreen grid of the normally open gate means 92 and in this fashionprovides gating voltage therefor. Also connected to the controlelectrode of the gaseous tube 95 is the lead 65 from the photoconductivetarget element of the vidicon 47 illustrated in FIGURE 3. lnitially, thegaseous triggering tube 95 is non-conducting and its anode potential ishighly positive maintaining the gate 92 in a conducting condition topermit passage of the clock pulses. Whenever the electron beam of thevidicon tube is deflected sufficiently, by virtue of the deilectioncurrent produced by the auxiliary deilectien channel, to strike theregistering mark B at the upper left hand corner of each matrix, apositive pulse appears on the lead 65 connnected to the photoconductivetarget. This positive pulse is of suiicient magnitude to overcome thenegative biasing on the control electrode provided by the biasing means96 causing the tube to conduct heavily. The conduction of the gaseoustrigger tube 95 causes a rapid drop of anode potential which istransmitted directly to the screen electrode of the normally open gate92 causing that gate to close and preventing further clock pulses frombeing applied to the auxiliary channel. The anode potential of thetetrode 92 rises removing the biasing on the control electrode of thenormally closed gate tube 94 permitting the clock pulses to pass to themain deeetion channel to initiate the scan of the now registered andaligned 32 X32 matrix.

Resetting Circuit In order to reset both the switching means 89, as wellas the individual bi-stable units of the auxiliary channel 74, there isprovided a manually actuated circuit operated from the output of thelast bi-stable unit of the main vertical sealer 71b to place the entirecircuit in condition to repeat the operation for a new matrix. A resetcircuit, indicated at 93, for the auxiliary defiection channel isconnected through a manually operated switch 99 and a lead 104 to thelast bi-stable element S5 of the vertical scale 71b. The reset circuit98 consists of a multiplicity of and gates 100, each coupled toindividual ones of thebi-stable elements 87. Each of the and gates 100consist of a pair of crystal diodes 101 and -2 having their respectiveanodes connected to a common terminal point. A resistor 103 connectedbetween the common terminal point and a source of positive Voltageprovides biasing for the igate, while a lead 105 carrying a positivereset pulse is connected between the terminal point and the common inputlead of the trigger tubes V1 and V2. The cathode of the diode 101 isconnected to the anode of the current generator controlling tu-be V3 ofeach bi-stable multivibrator while the cathode of the `diode 102, on theother hand, is connected to the lead 104 carrying the positive pulsefrom the vertical sealer 7i1b.

And gates of the type illustrated at 100 are 'characterized by the factthat if both crystal diodes are simultaneously driven positive thepotential at their common junction, to which the lead 105 is connected,is caused to rise thus applying a positive pulse to the trig- Iger tubesV2 and V1. Thus, if in any given bi-stable element the tube V3 is in anon-conducting condition; that is, its anode potential is high andconsequently its respective constant current generator is conducting,both of the diodes 101 and 102 will be simultaneously positive thusproducing a positive pulse at the output lead 105 which, through theaction of the trigger tubes V1 and V2, `reverses the states of the tubesV3 and V4 thus terminating the operation of the current generator. If,on the other hand, the tube V3 is in a conducting condition, its anodepotential is low and consequently no positive pulse appears on the lead10S and the bi-stable element remains in the same condition. Thus, bymeans of the and gates 100 those bi-s-table elements 87 which are in thestate that their associated current generators 88 are conducting arereversed resetting the auxiliary deiiection channel and reducing thedeflection coil current produced thereby to Zero.

In addition, a reset circuit 106 returns the gaseous trigger means 95 toa non-cond-ucting condition returning the normally open and normallyclosed gates to their initial operating conditions. There is provided atriode amplifying element 107 connected to th-e output of the verticalsealer 71b through the manually operated switch 99. The amplifier 107consists of a cathode, control electrode, and an anode, the latter ofwhich is connected to a source `'of voltage through -a suitable anoderesistor and the cathode of which is connected to a source of referencepotential such as ground through a suit-able cathode resistor. With theswitch 99 in the closed position, the positive pulse produced iby thelast bi-stable element 85 at the end of the scan is applied to theamplifier 107 which reverses its polarity. The now negative pulse iscoupled by a lead 108 to the diode 97 connected to the anode of thegaseous trigger tube 95. As is Awell known, gaseous tubes of the typeillustrated at 95 once iired Iare independent of grid voltage and canonly be reset -by reducing their anode potential below the criticalextinction voltage.

Thus, the negative pulse appearing on the lead 108 passes through thediode 97 reducing the anode voltage of the tube 95 ybelow the extinctionvoltage causing conduction to terminate. The cessation of conduction bythe tube 95 raises its anode voltage re-opening normally open gate 92 topass clock pulses 'fonce more to t-he auxiliary channel from theterminal 90. The conduction of the normally open gate 92, of course,reduces its anode voltage which, being connected to control theelectrode of the normally closed gate 94, applies a negative biasthereto causing that gate to cease con-ducting and preventing anyfurther clock pulses from lbeing applied to the main defiection channel71. rIhus, it can be seen that both the auxiliary and main deflectionchannels 71 and 74 are now in condition to repeat the operation. Clockpulses are again fed to the auxiliary channel until the indexing mark Bof the matrix is reached at which time another positive pulse appearsyon the lead 65 of the control electrode of the gaseous trigger at whichtime the gate 92 is once more closed, opening gate 94 and permitting themain deflection channel to scan the new block of data projected onto theface `of the vidicon tube.

A terminal connected to the last bi-stalble element S5 of the verticalscaler 71b of the main deflection channel 71 is connected to the readoutcontrol circuit 83, shown and discussed with reference to FIGURE 3, andprovides the trigger pulse for that control circuit to produce thesynchronizing pulse for operating synchronizing readout gate 68. It isobvious that only at the end of a vertical scan will a positive pulseappear at the terminal 110 in order to trigger the readout controlcircuit 83. It can be seen that the readout synchronizing pulse thusproduced enables the readout synchronizing gate 68 only at the beginningof a vidicon scan.

In discussing the data storage circuit of FIGURES 3 and 4, the storagetube `which translates the information matrix on the photographic dat-astorage element has, for illustrative purposes, been shown `anddescribed as a vidicon which is of the type having a photoconductivetarget structure. It is obvious to those skilled in the art that manyvariations and changes may be made in the type of storage tube utilizedwithout going outside the spirit and scope of this invention.

It is clear from the previous discussion that there has been provided adata storage system utilizing a photographic storage element which iscapable of large capacity, high storage density, high reliability, andrapid access. Furthermore, a readout system has been disclosed in whichthe readout and translation of the stored data is achieved by means of arough mechanical register of the desired block of data and exactcentering and registration thereof by ymeans of an electronic shiftingof the scanning center of :an image tube.

While a particular embodiment of this invention has been shown it will,of course, -be understood that it is not limited thereto since manymodifications both in the circuit arrangement and in theinstrumentalities employed may be made. It is contemplated by the-appended claims to cover any such modifications as fall within the truespirit and scope of this invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. In a data storage apparatus the combination comprising a photographicstorage element having data stored thereon in the form of individualexposure pattern matrices, means to translate said matrices intoelectrical output pulses including a photoconductive storage tube havinga scanning electron beam, optical light microscope projection meansincluding an achromatic lens system having a field fiattening lens toproject an enlarged image of entire individual matrices onto saidstorage tube, said tube operating to produce electrical pulsesrepresentative of the stored data as said electron beam scans the imageon said tube, means to control the scan field of said beam to align itwith said image including a main beam deiiection supply circuit and anauxiliary beam deflection supply circuit, said auxiliary circuit beingactuated to shift the beam scan until `a data indexing mark on saidmatrix image iS located and an output pulse is produced from saidstorage tube to disable said auxiliary circuit and energize said maincircuit in response to said pulse to control the further scanning ofsaid image.

2. In a data storage system the combination comprising a photographicstorage element having data stored thereon iu the form oi individualmatrices, means to translate the individual data matrices intoelectrical output pulse trains representative of said data, saidtranslating means including a storage tube means, optical lightmicroscope projection means including an achromatic lens system having afield iiattening lens for projecting an enlarged image of an entirematrix onto said storage tube means, scan control means associated withsaid storage tube means operative in response to an indexing mark onsaid matrix to align the tube scan iield with the projected image of onesuch matrix, pulse generating means connected to said scan control meansto initiate and synchronize operation thereof, and means actuated inresponse to output pulses from said storage tube means to apply pulsesfrom said pulse generating means selectively to a utilization circuit.

3. In a data storage system the combination comprising a photographicstorage element having data stored thereon in the form of individualmatrices, means to translate said data matrices into output puise trainsrepresentative of said data, said translating means including a storagetube readout device having a readout electron beam, beam scan controlmeans for said readout beam, a light microscope optical projectionclement including an achromatic lens system having a field liatteninglens positioned between said storage element and said storage tubereadout device to project an enlarged image of an entire data matrixonto said storage tube device, pulse generating means connected to saidbeam scan control means to initiate and synchronize said scan, means toapply pulses from said pulse generating means selectively to an outputcircuit in response to output pulses from said translating meansincluding gating means coupled to said pulse generating and said storagemeans, said gating means transmitting pulses from said generating meansin response tO the output pulses from said storage tube readout device.

4. In a data storage system the combination comprising a photographicstorage element having data stored thereon in the form of data matrices,each of said matrices cornprising an exposure pattern of discrete dots,projection light microscope optical means including an achromatic lenssystem having a eld iiattening lens to produce an enlarged spatial imageof said data matrices, electrooptical means having a predetermined fieldof view to translate the stored data in the matrices from the enlargedspatial image into electrical output pulses, mechanical positioningmeans for adjusting the position of said storage element in twocoordinates relative to said means for producing a spatial image so thatselected matrices are brought into substantial alignment with thereadout field of view of said electro-optical means, and means to shiftthe entire scan field of said electro-optical means electronically tofurther align it with said enlarged spatial image prior to reading outsaid data.

5. In a data storage apparatus the combination comprising a photographicstorage element having data matrices stored thereon in the form of anexposure pattern of discrete dots, projection light microscope opticalmeans including an acnromatic lens system having a field liattening lensto produce an enlarged image of said pattern, cathode ray beam readoutmeans having a predetermined field of scan, said readout means being sopositioned that the entire data matrices in the form of said enlargedpattern are projected thereon to be scanned by the cathode ray beam toproduce electrical output pulses representative of said data, and meansto shift the entire scan iield of said cathode ray means electronicallyto align it with said enlarged pattern prior to reading out said data.

6. In a data storage system the combination comprising a photographicstorage element having data stored thereon in tie form of individualmatrices, means to translate said data into output pulses including aphotoconductive storage tube having a scanning electron beam, projectionlight microscope optical means including an achromatic lens systemhaving a iield llattcning lens to form and project enlarged images ofentire individual matrices onto the viewing face of said photoconductivestorage tube, step scan beam deiiection means for said photoconductivestorage tube to scan said projected images and produce said output pulsetrains representative of said data, pulse generating means connected tosaid scan means to initiate and synchronize said step scan, means togate the output from said pulse generating means in synchronism with theoutput pulses from said photoconduetive storage tube including a firstgate means for passing the photoconductive storage tube output pulsesactuated in response to the initiation of said scan, a second gate meansfor passing pulses from said pulse generating means to a utilizationcircuit, said second gate being coupled to said tirst gate means andgated by photoconductive storage tube output pulses passed by said firstgate means to pass pulses from said generating means.

7. ln a date. storage apparatus the combination comprising a storageelement having a pattern of discrete transparent and opaque areasrepresenting stored data, means to project a beam of light through saidstorage element t0 produce an image of said pattern in space, projectionlight microscope optical means including an achromatic lenS systemhaving a iield iiattening lens for viewing said image and producing anenlarged spatial image of said entire pattern, electro-optical meanshaving a predetermined field of view of said enlarged image forconverting the stored data on said storage element into electricaloutput pulses representative of said data, and means to align said imageand the eld of View of said electro-optical means in response to anindexing mark on said pattern.

References Cited in the tile of this patent UNITED STATES PATENTS2,295,000 Morse Sept. 8, 1942 2,659,072 Coales Nov. 10, 1953 2,712,898Knutsen July 12, 1955 2,714,841 Dorner Aug. 9, 1955 2,714,843 HooverAug. 9, 1955 2,731,200 Koelsch Jan. 17, 1956 2,738,499 Sprick Mar. 13,1956 2,795,705 Rabinow June 11, 1957 2,807,728 ilburn Sept. 24, 19572,816,246 Bliss Dec. 10, 1957 2,817,041 Urry ec. 17, 1957 2,830,285Davis Apr. 8, 1958 2,843,841 King July 15, 1958 2,859,427 McNaney Nov.4, 1958 2,939,632 Demer June 7, 1960 2,950,465 Fox Aug. 23, 1960

7. IN A DATA STORAGE APPARATUS THE COMBINATION COMPRISING A STORAGEELEMENT HAVING A PATTERN OF DISCRETE TRANSPARENT AND OPAQUE AREASREPRESENTING STORED DATA, MEANS TO PROJECT A BEAM LIGHT THROUGH SAIDSTORAGE ELEMENT TO PRODUCE AN IMAGE OF SAID PATTERN IN SPACE, PROJECTIONLIGHT MICROSCOPE OPTICAL MEANS INCLUDING AN ARCHROMATIC LENS SYSTEMHAVING A FIELD FLATTENING LENS FOR VIEWING SAID IMAGE AND PRODUCING ANENLARGED SPATIAL IMAGE OF SAID ENTIRE PATTERN, ELECTRO-OPTICAL MEANSHAVING A PREDETERMINED FIELD OF VIEW OF SAID ENLARGED IMAGE FORCONVERTIING THE STORED DATA ON SAID STORAGE ELEMENT INTO ELECTRICALOUPUT PULSES REPRESENTATIVE OF SAID DATA, AND MEANS TO ALIGN SAID IMAGEAND THE FIELD OF VIEW OF SAID ELECTRO-OPTICAL MEANS IN RESPONSE TO ANINDEXING MARK ON SAID PATTERN.